The facts stated in each affidavit filed pursuant to this article shall be set forth with particularity. Except where matters are specifically permitted by this article to be shown by information and belief, each affidavit shall show affirmatively that the affiant, if sworn as a witness, can testify competently to the facts stated therein. The affiant may be any person, whether or not a party to this action, who has knowledge of the facts. A verified complaint that satisfies the requirements of this section may be used in lieu of, or in addition to, an ordinary affidavit.